From: NeilBrown <neil@brown.name>
Date: Tue, 24 Feb 2026 22:16:47 +0000 (+1100)
Subject: fs/proc: Don't lock root inode when creating "self" and "thread-self"
X-Git-Tag: v7.1-rc1~245^2^2~13
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9ab68389843a434d7d49e2a986ebf6d01d81ae42;p=thirdparty%2Fkernel%2Flinux.git

fs/proc: Don't lock root inode when creating "self" and "thread-self"

proc_setup_self() and proc_setup_thread_self() are only called from
proc_fill_super() which is before the filesystem is "live".  So there is
no need to lock the root directory when adding "self" and "thread-self".
This is clear from simple_fill_super() which provides similar
functionality for other filesystems and does not lock anything.

The locking is not harmful, except that it may be confusing to a reader.
As part of an effort to centralise all locking for directories for
name-based operations (prior to changing some locking rules), it is
simplest to remove the locking here.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20260224222542.3458677-3-neilb@ownmail.net
Signed-off-by: Christian Brauner <brauner@kernel.org>
---

diff --git a/fs/proc/self.c b/fs/proc/self.c
index 62d2c0cfe35c5..56adf1c68f7ac 100644
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -35,11 +35,9 @@ unsigned self_inum __ro_after_init;
 
 int proc_setup_self(struct super_block *s)
 {
-	struct inode *root_inode = d_inode(s->s_root);
 	struct dentry *self;
 	int ret = -ENOMEM;
 
-	inode_lock(root_inode);
 	self = d_alloc_name(s->s_root, "self");
 	if (self) {
 		struct inode *inode = new_inode(s);
@@ -55,7 +53,6 @@ int proc_setup_self(struct super_block *s)
 		}
 		dput(self);
 	}
-	inode_unlock(root_inode);
 
 	if (ret)
 		pr_err("proc_fill_super: can't allocate /proc/self\n");
diff --git a/fs/proc/thread_self.c b/fs/proc/thread_self.c
index d6113dbe58e05..61ac62c3fd9f8 100644
--- a/fs/proc/thread_self.c
+++ b/fs/proc/thread_self.c
@@ -35,11 +35,9 @@ unsigned thread_self_inum __ro_after_init;
 
 int proc_setup_thread_self(struct super_block *s)
 {
-	struct inode *root_inode = d_inode(s->s_root);
 	struct dentry *thread_self;
 	int ret = -ENOMEM;
 
-	inode_lock(root_inode);
 	thread_self = d_alloc_name(s->s_root, "thread-self");
 	if (thread_self) {
 		struct inode *inode = new_inode(s);
@@ -55,7 +53,6 @@ int proc_setup_thread_self(struct super_block *s)
 		}
 		dput(thread_self);
 	}
-	inode_unlock(root_inode);
 
 	if (ret)
 		pr_err("proc_fill_super: can't allocate /proc/thread-self\n");